Thermal power point


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Thermal power point

  2. 2.  A Thermal Power Plant converts the heat energy of coal into electrical energy. Coal is burnt in a boiler which converts water into steam. The expansion of steam in turbine produces mechanical power which drives the alternator coupled to the turbine.Thermal Power Plants contribute maximum to the generation of Power for any country  Thermal Power Plants constitute 75.43% of the total installed captive and non-captive power generation in India  In thermal generating stations coal, oil, natural gas etc. are employed as primary sources of energy.
  3. 3.  Coal handling plant  Pulverizing plant  Draft fans  Boiler  Ash handling plant  Turbine  Condenser  Cooling towers and ponds  Feed water heater  Economizer  Superheated and Reheated  Air preheated
  4. 4. Raw Coal Wagon- Coal is brought to the site through a Wagon as per requirement. Wagon tippler-The coal is unloaded from the Wagon and is transported to crushers and for storage place through conveyor. Junction tower- JT’s are used where the conveyor has any angular deviation. Primary Crusher-The Raw coal is crushed into fine pieces to 45mm grit). Primary crusher is also called Rotary Breaker since the coal is crushed by a rotating plate. Rejected- The stones and unwanted coal is rejected Coal Handling Plant
  5. 5. Stacker & Reclaimer- It is used to store the powdered coal for emergency purpose Two way conveyor Atmospheric air (Through FD fan) Junction Tower Mill Bunker-The 25mm grit coal is crushed into very fine powder for feeding the boiler. We will have a spare Bunker for each Boiler. BOILER Secondary Crusher-The fine pieces of coal is crushed to powder (to 25mm grit)
  6. 6.  In modern thermal power plant , coal is pulverized i.e. ground to dust like size and carried to the furnace in a stream of hot air. Pulverizing is a means of exposing a large surface area to the action of oxygen and consequently helping combustion.  Pulverizing mills are further classified as: 1. Contact mill 2. Ball mill 3. Impact mill
  7. 7.  The circulation of air is caused by a difference in pressure, known as Draft.  Draft is a differential pressure b/w atmosphere and inside the boiler.  It is necessary to cause the flow of gases through boiler setting  It may be – 1. Natural draft 2. Mechanical draft
  8. 8. Air Air Fuel HFO,LDO & Coal Boiler Fuel HFO,LDO & Coal Dryer Air compressor FD Fan Atmospheric Air The boiler is fed with HFO and LDO initially to ignite the coal in the Boiler. Types of boilers: 1. Water tube Boiler: A boiler in which water circulates in tubes heated externally by the fire. 2. Fire tube Boiler: Water is present in the drum inside the boiler and Hot air is circulated around maintain the temperature. •The fuel and air are feed from 2 directions to increase the efficiency
  9. 9. The Ash from the boiler is collected in two forms: 1. Bottom Ash(Slurry):It’s a waste which is dumped into a Ash Pond 2. Fly ash: Fly ash is separated from Flue Gases in ESP(Electro static Precipitator). Fly Ash & Flue Gases Economizer ESP Bottom ash(wet ash) Ash Pond Boiler Cylo Cement Factory Economizer : Reduces the temperature Chimney Fly ash Flue Gases Flue Gases
  10. 10. In a Thermal Power Plant generally 3 turbines are used to increase the efficiency.  High Pressure Turbine(HPT): The superheated steam is directly fed to this turbine to rotate it.  Intermediate Pressure Turbine(IPT): The out put from the HPT is reheated in a reheated(RH) and used to rotate IPT .  Low Pressure Turbine(LPT): The Exhausted steam from the IPT is directly fed to rotate the shaft of LPT. Condenser HPT IPT LPT RH Steam Super Heater Generator Steam Shaft *All the turbines are connected to a single shaft which is connected to the Generator.
  11. 11.  Steam after rotating steam turbine comes to condenser. Condenser refers here to the shell and tube heat exchanger (or surface condenser) installed at the outlet of every steam turbine in Thermal power stations of utility companies generally.
  12. 12. o A condenser needs huge quantity of water to condense the steam . o Typically a 2000MW plant needs about 1500MGallon of water. o Most plants use a closed cooling system where warm water coming from condenser is cooled and reused o Small plants use spray ponds and medium and large plants use cooling towers. o Cooling tower is a steel or concrete hyperbolic structure having a reservoir at the base for storage of cooled water o Height of the cooling tower may be 150 m or so and diameter at the
  13. 13.  Advantages of heating water before feeding back to the boiler:- a) Feed water heating improves overall plant efficiency. b) The dissolved oxygen and carbon dioxide which would otherwise cause boiler corrosion are removed in feed water heater c) Thermal stresses due to cold water entering the boiler drum are avoided. d) Quantity of steam produced by the boiler is increased. e) Some other impurities carried by the steam and condensate, due to corrosion of boiler and condenser are precipitated outside the boiler
  14. 14.  Flue gases coming out of the boiler carry lot of heat. An economizer extracts a part of this heat from flue gases and uses it for heating feed water. This use of economizer results in saving coal consumption and higher boiler efficiency
  15. 15.  Super heater :  Super heater is a component of a steam- generating unit in which steam, after it has left the boiler drum, is heated above its saturation temperature  Reheater : Some of the heat of superheated steam is used to rotate the turbine where it loses some of its energy
  16. 16.  After flue gases leave economizer, some further heat can be extracted from them and used to heat incoming heat. Cooling of flue gases by 20 degree centigrade increases the plant efficiency by 1%.  Air preheaters may be of three types  Plate type  Tubular type  Regenerative type
  17. 17. Water in a Power Plant is used for 1. Production of Steam- for rotating turbine. 2. Cooling Purpose- For cooling of various equipment . Water is recycled and used for various purpose: 3% of water is wasted during this process. Appx 4 cubic mt water is lost /day/MW Raw Water Purified DM water For cooling purpose Steam Conden ser
  18. 18. Reservoir Water Clarification DM Plant (Demineralized Plant) Chlorification & Filtration Various Equipment Cooling Water Cooling Tower CT Auxiliary cooling Water (ACW) DMCWP DMCW Demineralized cooling Water CWPCT CWP CWP Condenser Boiler Steam water Cool water Hot water Hot WellDearator 25D  35D 25D  20D PHE Various Equipment D-Degrees CWP-cooling water Pump PHE-Pre heat Exchange Water Cycle
  19. 19.  The coal is brought and crushed to powder. This is feed to Boiler for producing heat  In Boiler the water is converted to steam.  In Super heater the moisture content is removed from the steam and that steam is called super heated steam  The superheated steam rotates the shaft of the High pressure turbine  The Exhausted steam is sent to preheater and the steam then rotates the Intermediate pressure(IP) Turbine  The steam from the IP turbine is then feed to low pressure turbine.  The turbine shaft is connected to the Generator, which produces Electric Power.  The power generated is then Transmitted.
  20. 20. The Synchronous Generator is used to Generate power by connecting the shaft of the Turbine to the shaft of the generator which cuts the magnetic flux producing Emf.  The Generated Voltage will generally 11KV to 20 KV max.  The Generated Voltage is stepped up by connecting Step up transformer and is transmitted and is also used for Auxiliary purposes. Bus Duct Generator Transformer 20KV to 400KV SYNCHRONOUS GENERATOR UAT 20Kv to 6.KV Unit Auxiliary Transformer: This transformer is used to step down the produced voltage and use for Auxiliary purpose.